This is a crazy project for controlling a musical holiday lights show. I built a toolbox-based controller for 48 independent outlets, driven by relays, controlled by a Raspberry Pi and a custom i2c breakout board ased on the MCP23017 chip.
Each MCP23017 chip can take the i2c control input and assign addresses for up to 16 outputs, increasing the options from the standard GPIO pins on the Pi. This breakout board uses 3 MCP23017s for a total of 48 relays (6 boards of 8). I should note that each relay board is powered from a 12V laptop power supply that goes through a beefy 5V regulator. The breakout board is powered by 5V and 3V3 from the Pi.
I use midi files to sequence the lights, with linkages defined between note values and relay addresses in midimap.json. Creating the midi files is a whole other discussion. I first loaded the wav file into a digital audio workstation, corrected the timing through the song, and then recorded the notes that corresponded to each individual light string into a midi track. It takes a while to set up each midi file, but the note_on and note_off messages make it very convenient to turn on and off the relays. mido makes it incredibly easy to parse through a midi file and read each message, which then get parsed into a queue.
The file raspilights.py was my original attempt that uses a subprocess call to play for wav file playback. This led to wildly unpredictable differences in when the music started vs. when the light sequence started. It works ok, but I wanted more control.
pg_raspilights.py uses pygame to playback the wav file and it's timed to start as soon as the midi messages start getting parsed into the thread queue.